This invention relates to trocar sleeves (sometimes referred to an cannuli), of the kind having a widened part forming a housing between the distal portion of the sleeve and its proximal portion, which latter extends from a plug for the widened housing part, and a ball valve in the widened housing part which ball valve is normally closed by resilient means and which is openable by a trocar passing through the sleeve. Hereinafter such a trocar sleeve will be referred to as "of the kind described".
It is known to provide trocar sleeves or cannuli between their proximal and distal portions with a widened part which forms a housing and in which a magnetic flap valve is resiliently mounted, as described in German Gebrauchsmuster No. 7,430,345 and British Patent Specification No. 1,482,857, so that the sleeve may be sealed after the trocar has been withdrawn and in this way any escape of gas from say, an abdominal cavity, can be prevented. Practical experience has shown that after a given period of time an arrangement of this kind no longer performs its appointed function.
It is also known as described in German Auslegeschrift No. 1,267,377 to fit, in the widened proximal part of the sleeve, a ball valve whose ball is pressed against a valve seating by a tangentially loaded helical spring but is able to move aside when the trocar or an instrument is passed through. This known design results in the sleeve having an eccentrically projecting widened portion and is expensive.
It is an object of the invention to simplify the construction of a ball valve and its fitting to a trocar sleeve of the kind described, with the valve seating accurately aligned, and to reduce manufacturing costs while providing a long life.